The present application claims priority under 35 U.S.C. xc2xa7119 of German Patent Application No. 198 22 185.1, filed on May 16, 1998, the disclosure of which is expressly incorporated by reference herein in its entirety.
1. Field of the Invention
The present invention concerns a device for the cleaning of a transport (conveyor) belt, e.g., a dry or wet wire belt or a felt belt, of a machine for the production or processing of a web, e.g., a paper or cardboard web. The device includes at least one nozzle device having at least one cleaning nozzle to deliver a cleaning jet aimed at the transport belt. In this manner, the cleaning nozzle is rotatably installed on a nozzle head of the nozzle device to be rotated around an axis, and the nozzle device is arranged on a transport device that is displaceable along a crosspiece extending crosswise or substantially crosswise to a transport belt travel direction.
The present invention is related to a process for the cleaning of a transport belt, e.g., a dry or wet wire belt or a felt belt, of a machine for the production or processing of a web, e.g., a paper or cardboard web. The process includes rotating at least one cleaning nozzle around an axis, aiming a cleaning jet from the at least one cleaning nozzle toward the transport belt, and displacing the at least one cleaning nozzle crosswise to a transport belt travel direction.
2. Discussion of Background Information
Cleaning devices and processes of the type generally discussed above have been disclosed, e.g., in German Patent No. DE 195 39 015 C2, the disclosure of which is expressly incorporated by reference herein in its entirety. The disclosed device and process are utilized in connection with a material web production or processing machine to clean a transport (conveyor) belt which has become soiled during operation of the machine. In the process, the meshes and pores of the porous transport belt become clogged with paper fibers, adhesives, or other additions. To ensure problem-free operation of the transport belt, cleaning of the transport belt is necessary, e.g., with a cleaning device that includes at least one nozzle device, which has the at least one cleaning nozzle installed on a nozzle head that rotates around an axis. Using the cleaning nozzle, a cleaning jet, e.g., a liquid stream, can be aimed at the transport belt. To improve the cleaning effect of the rotating cleaning nozzle, the nozzle device is disposed on a transport device, which is displaceable along a crosspiece running crosswise to the transport belt travel direction. The traversing speed in the known cleaning device falls within a range from approximately 0.1 m/min to approximately 0.5 m/min. Due to the fact that a linear traversing motion is superimposed on the rotary motion of the cleaning nozzle, a relatively broad band-shaped region of the transport belt is cleaned instead of a line.
It has been demonstrated that, due to the rotation of the cleaning nozzle, the cleaning effect is amplified in the sections of the circle which lie roughly in the direction of travel of the transport belt. This irregular cleaning of the transport belt cannot be equalized despite the traversing motion of the cleaning nozzle. Thus, the moisture profile of the transport belt, which affects the properties of the paper or cardboard web and should be as low and as uniform as possible, cannot be adjusted as desired. This results due to the fact that, in the regions in which an amplified cleaning effect occurs, the transport belt is more highly soaked than in the regions of the transport belt in which the cleaning nozzle cleans with reduced cleaning effect. To date, the known cleaning devices are operated with a compromise between adequate cleaning effect and a simultaneously relatively low moisture profile of the transport belt. However, it has been shown that it is not possible in all cases to realize a low and particularly uniform moisture profile of the transport belt, and a good cleaning effect of the cleaning device.
Therefore, the present invention improves the cleaning device as generally discussed above and the process implemented with the cleaning device that does not suffer from the above-noted disadvantages.
The cleaning device according to the present invention includes a nozzle device that is displaceable, on a crosspiece during the cleaning process, into a plurality of cleaning positions lying one after the other (successively arranged) in the transport belt travel direction, in which the nozzle device is held stationary for a predefined, and in particular, variable period of time in each respective cleaning position. Further, a change between cleaning positions occurs suddenly. In connection with the present invention, the term xe2x80x9csuddenlyxe2x80x9d is understood to mean, e.g., a rapid displacement at a relatively high speed. Thus, displacement of the nozzle device on the crosspiece from one cleaning position to the next occurs very quickly, such that, in each region of the surface of the transport belt, a predefined, and preferably substantially equally long, duration of action can be realized. The period of time in which the cleaning nozzle or the nozzle device is disposed in a cleaning position can be varied, e.g., as a function of the degree of soiling, of the machine speed, of the moisture profile of the transport belt, and/or the rotational speed of the nozzle head. Through the discontinuous displacement of the nozzle device from one cleaning position to the next, a good cleaning effect can be realized with a simultaneously low moisture profile.
In an exemplary embodiment of the cleaning device, a distance between two adjacent cleaning positions may correspond to the cleaning width, e.g., at least substantially to the cleaning width of the cleaning nozzle rotating around an axis. Thus, in each cleaning position, a band-shaped section of the transport belt is cleaned, and adjacent sections abut each other.
Further, a traversing speed of the nozzle device can be very low and falls within a range between approximately 1 mm/min and 10 mm/min, and preferably between approximately 2 mm/min and 5 mm/min. Thus, it is possible to ensure that the duration of action of the cleaning jet coming from the cleaning nozzle, e.g., air, steam, or a liquid stream, reaches a minimum value at each location or region of the transport belt. In other words, due to the very slow displacement of the nozzle device over the entire width of the transport belt, it is possible to obtain a desired, and preferably uniform and intense, cleaning action such that it is advantageously possible to realize at the same time a uniform moisture profile of the transport belt. The duration of action of the cleaning jet on the transport belt is set, e.g., as a function of the degree of soiling of the transport belt and the type of paper or cardboard web, which is determined, e.g., by its ash content and pulp density. The traversing speed may preferably be set as a function of the machine speed, i.e., the speed of travel of the material web.
In the process for the cleaning of a transport belt of a machine for the production or processing of a paper or cardboard web, at least one cleaning nozzle, which is displaceable crosswise to the transport belt travel direction and rotatable around an axis, is used. A cleaning jet, e.g., a steam or liquid jet, ejected from the at least one cleaning nozzle, can be aimed at the transport belt. The process further includes displacing the cleaning nozzle very slowly and, preferably, with a constant traversing speed over the width of the transport belt. The traversing speed may fall within a range between approximately 1 mm/min and 10 mm/min, and preferably between approximately 2 mm/min to 5 mm/min.
During the cleaning process, the cleaning nozzle may assume a plurality of (discrete) cleaning positions lying one after another crosswise to the transport belt travel direction, and may stay in each of the cleaning positions for a predefined period of time. Further, the cleaning nozzle may be rapidly repositioned between adjacent cleaning positions so as to ensure a uniform cleaning action of the cleaning nozzle over the entire width of the transport belt. As a result, a relatively low and uniform moisture profile of the transport belt may be set.
The present invention is directed to a process for cleaning a transport belt of a machine for the production or processing of a web. The machine has an apparatus that includes at least one nozzle device composed of a rotatable nozzle head having at least one cleaning nozzle adapted to deliver a cleaning jet aimed toward the transport belt, a transport device that includes a crosspiece extending substantially crosswise to a transport belt travel direction. The at least one nozzle device is coupled to the transport device, and the at least one nozzle device is coupled and adapted for displacement along the crosspiece. The process includes displacing the at least one cleaning nozzle along the crosspiece at a very slow traversing speed within a range of between approximately 1 mm/min and 10 mm/min. Further, the very slow traversing speed may be within a range of between approximately 2 mm/min to 5 mm/min, and the very slow traversing speed may be a substantially constant traversing speed. Further still, the transport belt may be composed of one of a dry or wet wire belt or a felt belt, and the machine may produce or process a web composed of one of a paper and a cardboard web.
The present invention is also directed to a process for cleaning a transport belt of a machine for the production or processing of a web. The process includes discontinuously moving the at least one cleaning nozzle along the crosspiece to a plurality of cleaning positions successively arranged in a transport belt travel direction, positioning the at least one nozzle to remain in the cleaning positions for a predefined period of time, and rapidly displacing the at least one nozzle between adjacent cleaning positions.
In accordance with another feature of the present invention, after being positioned over a cleaning position located at a lateral edge of the transport belt, the process further includes rapidly repositioning the at least one cleaning nozzle to the other lateral edge of the transport belt.
According to another feature of the present invention, the cleaning process may be initiated at a lateral edge of the transport belt.
According to still another feature of the present invention, a maximum distance between adjacent cleaning positions may correspond to the cleaning width of the rotating cleaning nozzle.
In accordance with a further feature of the present invention, a distance between adjacent cleaning positions may be within a range of between approximately 2 mm to 100 mm, and preferably within a range of between approximately 10 mm and 50 mm.
In accordance with a still further feature of the present invention, a period of time in which the cleaning nozzle remains in a respective cleaning position is within a range of between approximately 0.1 min and 10 min, and preferably the period of time may be between approximately 1 min to 5 min.
The present invention is directed to an apparatus for cleaning a transport belt of a machine for the production or processing of a web. The apparatus includes at least one nozzle device composed of a rotatable nozzle head having at least one cleaning nozzle adapted to deliver a cleaning jet aimed toward the transport belt, a transport device including a crosspiece extending substantially crosswise to a transport belt travel direction, in which the at least one nozzle device is coupled to the transport device and is adapted for displacement along the crosspiece. The at least one nozzle is positionable in a plurality of cleaning positions that are successively arranged crosswise to the transport belt, and the at least one nozzle is held stationary in each respective cleaning position for a predefined time period.
In accordance with another feature of the present invention, the at least one nozzle may be moved between adjacent cleaning positions such that a transition time between adjacent cleaning positions is less than the predefined time period.
In accordance with still another feature of the present invention, a distance between two adjacent cleaning positions may substantially correspond to a cleaning width of the at least one nozzle.
According to still another feature of the present invention, upon reaching a lateral edge of the transport belt, the cleaning nozzle may be rapidly displaceable to the other lateral edge of the transport belt.
The present invention is also directed to an apparatus for cleaning a transport belt of a machine for the production or processing of a web. The apparatus includes at least one nozzle device composed of a rotatable nozzle head having at least one cleaning nozzle adapted to deliver a cleaning jet aimed toward the transport belt, a transport device including a crosspiece extending substantially crosswise to a transport belt travel direction, in which the at least one nozzle device is coupled to the transport device and is adapted for displacement along the crosspiece. The traversing speed of the nozzle device is very low and falls within a range of between approximately 1 mm/min and 10 mm/min, and preferably between approximately 2 mm/min and 5 mm/min.
According to yet another feature of the present invention, the nozzle device is adapted for substantially constant traversing speed during displacement from one lateral edge of the transport belt to the other lateral edge.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.